1. Field of the Invention
The invention pertains to electronic entry keyboards. Entering text and/or numerical and/or special characters is often very tedious for the users of many small pieces of equipment, such as telephones, fax machines, small computers, and so forth. In mobile phones or cordless phones, for example, text characters are typically input by pressing certain number keys more than once; ASCII characters are assigned to the number keys in a standardized way (for instance by the ITU--International Telecommunications Union). Special characters are assigned to the 0, 1, * or # keys, for instance, or are added following the ASCII characters. Thus each key is assigned more than once. The "3" key, for instance, is assigned the character series {D E F 3 . . . }. Pressing the key once, twice, three times, etc. within a predetermined time period (or a time period that is adjustable by the user or the service technician), typically 800 ms, causes the character D, E, or F, etc. to be input.
Instead of pressing a key multiple times, depressing the key for a long time can also cause the characters to change over time in an autoscrolling process. Other versions are based on cursor keys, with which the intended characters can be selected from the entire linearly arranged alphabet or some other character set.
Special problems often arise when shifting from upper- to lower-case writing (or vice versa) while texts are being input (for instance in a Short Message Service), or when entering names (electronic telephone book in a communications terminal). In most mobile phones, the switchover (shift key function) between upper-case and lower-case writing is accomplished in one of the following ways:
In one prior art concept, the shift key function is effected with a so-called soft key or a dedicated key. The shift is then usually permanent, i.e., it is equivalent to the Caps Lock key on a PC keyboard. Due to the fact that only a few characters--often the first letter of a word--need to be entered in upper-case form, the Caps Lock mode is not very user-friendly. In another prior art concept, depressing a key for a prolonged time is used to shift from upper-case to lower-case. This leads to frequent typographical errors. A third prior art version places the capital letters after the lower-case letters in the multi-character series on each key, which makes for very time-consuming entering procedures.